For those who are unaware an 'Error 404' is hyper text transport protocol talk for "hi there, i'm the web server you just tried to request a page from - and guess what? It doesn't exist - well at least not under the name you're calling it'
I'm sure you've seen them a million times. In a previous life I customised them on a government server so that they were a bit more helpful than 'We don't got any!' - so they'd maybe have a link to a site map and the site search tool.
Some people do this a lot don't, sadly.
I just came across one that I wanted to share:
If you come across any please share....
Oh yeah, if your an IE user remember to go into Tools|Internet Options|Advanced and turn off 'Show Friendly HTTP Error Messages'